Helga the Viking from the episode "Dear Vikings"

Honestly the hottest girl in Sponge Bob, not that there's a lot of competition. The way they had to tone down the concept art is hilarious.

Also included the palette swap 2nd viking girl, which is exactly the same character just colored differently.
"furry female, anthro fish, fish girl, purple skin, colored skin, black hair, twin braids, green bow, pink lips, lipstick, green eyes"